# 空气质量查询
def grade(score):
    if 0 <= score <= 50:
        print('空气质量为：优')
    elif 51 <= score <= 100:
        print('空气质量为：良')
    elif 101 >= score >= 150:
        print('空气质量为：轻度污染')
    elif 151 <= score <= 200:
        print('空气质量为：中度污染')
    elif 201 <= score <= 300:
        print('空气质量为：重度污染')
    else:
        print('空气质量为：严重污染')


for score in range(10):
    score = int(input('请输入您的PM2.5值：'))
    grade(score)